Author Topic: Screaching Bearings- Astonishing Effects  (Read 1327 times)

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woodone

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Re: Screaching Bearings- Astonishing Effects
« Reply #15 on: February 19, 2020, 01:20:49 PM »
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Most worm-worm wheel drives use different materials for the worm (steel most of the time) and a brass/bronze worm wheel.
If the same materials are used the gears seam to gall and wear out real quick.Has for hardened shafts, I don’t think the models we are working with here demand a very hard shaft. A brass shaft? Way too soft! Any good steel shafting material from places like NWSL or Mc Master Carr will outlast most of us.
It’s the dirt/debris that gives us problems.

Doug G.

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Re: Screaching Bearings- Astonishing Effects
« Reply #16 on: February 20, 2020, 04:00:18 PM »
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A simple test is to take a mill file across it, if it takes metal off it's not considered "hardened". Otherwise you can use a hardness tester, but it will leave a divot. I have one sitting next to me :)

Oops, clicked on wrong post.

Doug
« Last Edit: February 20, 2020, 04:03:06 PM by Doug G. »
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Doug G.

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Re: Screaching Bearings- Astonishing Effects
« Reply #17 on: February 20, 2020, 04:04:07 PM »
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I wonder if the worm gear is also brass? Hard to see, but it might be. That would likely cause excessive wear.

I think that kind of wear (sharp worm edges) occurs from insufficient mesh and the ends get excessively worn. It's hard to get it to stop even readjusting mesh. You usually have to use a new worm. Some mechanisms are extremely touchy for this. The old Arnold steamers, for example.

Doug
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peteski

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Re: Screaching Bearings- Astonishing Effects
« Reply #18 on: February 20, 2020, 04:33:37 PM »
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I think that kind of wear (sharp worm edges) occurs from insufficient mesh and the ends get excessively worn. It's hard to get it to stop even readjusting mesh. You usually have to use a new worm. Some mechanisms are extremely touchy for this. The old Arnold steamers, for example.

Doug

Whatever it was, I have feeling that Ron will do something about it. He is pretty familiar with N scale mechanicals.  What surprises me is that he did not mention what he found to have caused the unusual worm wear.  He is usually pretty thorough in that regard.

@u18b ?
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u18b

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Re: Screaching Bearings- Astonishing Effects
« Reply #19 on: February 20, 2020, 10:35:17 PM »
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Whatever it was, I have feeling that Ron will do something about it. He is pretty familiar with N scale mechanicals.  What surprises me is that he did not mention what he found to have caused the unusual worm wear.  He is usually pretty thorough in that regard.

@u18b ?

It had to be the stupid rubber hose connection.  It is inherently uneven, and it is too fat in that it slightly scrapes the base plate.  Thus since it is uneven, it causes the joint to bounce up and down.

If you own a Shay, I would do what I did and replace that rubber joint.

What bugs me is that I have another Shay, and while it runs pretty well, I fear the bearings in it may already have some slight damage.

Ron Bearden
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peteski

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Re: Screaching Bearings- Astonishing Effects
« Reply #20 on: February 20, 2020, 11:31:08 PM »
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It had to be the stupid rubber hose connection.  It is inherently uneven, and it is too fat in that it slightly scrapes the base plate.  Thus since it is uneven, it causes the joint to bounce up and down.


I'm not sure how to interpret that Ron. Are you saying that the rubber universal coupling somehow cause the worm's edges to get sharp?  How does that relate?
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u18b

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Re: Screaching Bearings- Astonishing Effects
« Reply #21 on: February 20, 2020, 11:45:40 PM »
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Sorry reading fast and not paying attention.
I answered the - how did the bearings get so bad question.

As for the worm, yes, one or more theorized the mesh was bad.

It was tight enough (you have no control over that, but the worm and the worm gear are not at exactly the same level.
The worm is higher- and that's where there is no elevation in the bearings.  If you install the fiber washer/pads (for vibration reduction I assume) then the height is even greater.

Probably the best mesh is achieved with bearing holders mounted right on the base (no fiber washers) and a washer under the worm gear to raise it.


« Last Edit: February 21, 2020, 12:11:49 PM by u18b »
Ron Bearden
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peteski

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Re: Screaching Bearings- Astonishing Effects
« Reply #22 on: February 20, 2020, 11:48:13 PM »
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The worm is brass. Is the worm gear also brass? Not readily apparent in the photos.  If they are both brass, that can cause excessive wear.
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u18b

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Re: Screaching Bearings- Astonishing Effects
« Reply #23 on: February 21, 2020, 12:05:36 AM »
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Yes.  They are both brass.

While we're on the subject, the upper worm, worm gear and transition gear all all brass.

The transition gear spins a perpendicular shaft hidden in the cylinders.

Down there at the bottom of that shaft is another worm, but it looks steel.
This interfaces with a steel gear in the crankshaft.

So brass on brass up top and steel on steel below.
Ron Bearden
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"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.

woodone

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Re: Screaching Bearings- Astonishing Effects
« Reply #24 on: February 21, 2020, 08:56:51 AM »
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WOW! Looks like you have really opened up a can of worms.- Is this all O.E.?
Brass against brass is really not good, nor is steel to steel.
I would think in this drive you have a worm driving a worm wheel which is an idler. The idler drives a vertical shaft which has another worm that turns a gear on the crankshaft?
Maybe you can mount the vertical shaft/worm at a different angle and get rid of the idler?
The steel to steel drive to the crank might be a real problem- getting a brass gear on the crankshaft could be a deal breaker.
Don’t think this is a one night work project.

narrowminded

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Re: Screaching Bearings- Astonishing Effects
« Reply #25 on: February 21, 2020, 10:52:01 AM »
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Are the worms the same pitch and diameter?  If so, could the shaft be inverted?  Steel on brass isn't a bad combination.  Is it possible that it was assembled that way in error?  Just some thoughts. :|
Mark G.

u18b

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Re: Screaching Bearings- Astonishing Effects
« Reply #26 on: February 21, 2020, 12:14:41 PM »
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My sound decoder should be arriving in a day or two.  When it does, I'll post more pics on these gears.

By the way, I sort of treat this loco like the real thing.   I lubricate it a good deal.    There are a LOT of metal moving parts.  Grease on the gears and oil on all bearings and joints.
Ron Bearden
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u18b

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Re: Screaching Bearings- Astonishing Effects
« Reply #27 on: February 21, 2020, 12:26:16 PM »
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Hi folks.

This thread is evolving (which is good).

Since the original intent of the thread from the first post is fulfilled, I suggest we move this discussion to a fresh thread with a more reflective title.

So let's stop this thread here and I'll start a new thread (which I intended to do all along- this seems like a good time.)
Ron Bearden
CSX N scale Archivist
http://u18b.com

"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.